Apparatus for making metallic pipes and tubes



Dec. 29, 1942. w, MOHAN 2,306,827

APPARATUS FOR MAKING METALLIC PIPES AND TUBES Filed Oct. 24, 1940 3 Sheets-Sheet l Dec. 29, 1942. w. -T. MOHAN APPARATUS FOR MAKING METALLIC PIPES AND TUBES 3 Sheets-Sheet 2 Filed Oct. 24, 1940 Dec. 29, 1942. w. T. MOHAN 2,306,827

APPARATUS FOR MAKING METALLIC PIPES AND TUBES.

Filed Oct. 24, 1940 3 Sheets-Shet 5 I closely illustrating a Patented Dec. 29, 1942 UNITED STATES PATENT OFFICE APPARATUS FOR MAKING LIETALLIC PIPES AND TUBES William T. Mohan, Pittsburgh, Pa.

Application October 24, 1940, Serial No. 362,690

2 Claims.

This invention relates to the manufacture of metallic pipes and tubes and more particularly to the "seamless" process employed therein.

In the manufacture of seamless pipes and tubes, molten steel is cast into large ingots which are subsequently reduced to billet size, reheated and pierced to form a tubular blank by passing the billet between a pair of rolls and over an intermediately disposed piercing point. The rolls advance the billet helically and the piercing point is carried in such manner as to resist thrust on the forward end of a mandrel bar which is free to rotate with the billet. The tubular blank, as it emerges from the rolls, passes over themandrel bar which, of course, must be longer than the blank to be formed. Consequently, the man'- drel bar is of appreciable length as compared with its diameter, therefore tends to sag, and when rotating, whips or vibrates excessively.

It is among the objects of the present invention to restrain the excessive vibration of mandrel bars which support mandrels or piercing points in the manufacture of seamless pipes or tubes.

Another object is the provision of a device of the class described which is not only comparatively cheap and simple to manufacture and operate but one which is at the same time susceptibie of use on'mandrel bars which vary in length and diameter over wide ranges. There are at present devices which are constructed and arranged-to restrain excessive vibration of these mandrel bars but they require changing for every change made in the diameter of the mandrel bar; and this, of course, consumes considerable time with attendant loss of production. I

Other objects and advantages will appear as the nature of the improvements is better understood, the invention consisting substantially in the novel arrangement and correlation of parts hereiniully described and illustrated in the acdrawings, wherein similar reference characters are used to describe corresponding parts throughout the several views, and then finally pointed out and speciflcallydeiined and indicated in the appendedclaims.

In said drawings: Figure iisaaticplanofaseamless pipe or'tube mill employing the apparatus ofthe present invention: g g

Figure 2 is a'n enlarged fragmentary plan more part ofthe apparatuslof the present invention and its correlation with thcoutletbodorthemill oiFigure 1;

Figure 3 is a sectional view on the line III--III of Figure 2; and

Figure 4 is a view similar to Figure 3 but disclosing the operative elements thereof in different positions to accord with other phases of the operation thereof.

Referring more particularly to the drawings, the numeral 2 generally designates a pair of power-actuated metal working rolls which are conventionally used in the manufacture of seamless pipes and tubes, the rolls in the present instance being barrel-shaped and, therefore, known in the art as being of the Mannesman type. Disposed between the metal working rolls 2 is a conventional mandrel 3 in the form of a piercing point which is adapted to resist the thrust of a solid billet which is gripped by the metal working rolls 2 and moved helically therethrough and, accordingly, over the piercing point 3 in order to form a tubular blank from which a pipe or tube of the desired size is obtained. In accordance with conventional practice, the piercing point 3 is maintained against thrust by way of being carried on the forward end of a mandrel bar 4 which extends over the outlet bed of the mill. generally designated hereinafter at 5, and is carried on its rearward end by a carriage 6 which, in the operative position of the piercing point 3, is locked in order to resist thrust.

As the billet is pierced by passage between the metal working rolls 2 and over the piercing point 3 and progresses onto the outlet end of the mill, it moves over the mandrel bar 4 which, after the completion of the piercing operation, is withdrawn by the rearward movement of the carriage 8 in such manner as to free the interior of the tubular article therefrom. As the mandrel bar I is withdrawn over the outlet bed 5 of the the mandrel bar 4 is returned to its original poa sition preparatory to piercing another billet.

As indicated by the length-of the tubular blank hereinafter designated at X, and the length of the mandrel bar 4, over which it progresses, it will be perceived that the latter, due to sa ging.

, is subjectto excessive vibration or whipping, the

, present invention.

elimination of which is the prime object of the Referring more particularly to there is extended at suitable intervals along the outlet bed 5 of the mill a pair of parallel supports l which lie below and extend parallel with the Figures 3 and 4, Q

center line of the mandrel or piercing point 3 which is supported on the mandrel bar 4.

According to the teachings of the present invention, there is provided on the outlet bed of the mill and carried by the supports, series of rollers i0, Ii and [2. The rollers II and I2 are carried by parallel shafts l3 and H which are mounted on a suitable carriage generally designated at i6. This carriage I6 is moved in such a manner as to cause the rollers II and I2 to advance toward or recede from the center line of the pass of the mill in a manner which will be more fully described hereinafter.

The carriage I6 is slidably mounted on a housing l8 and is connected to a block 20 which is slidably disposed in the latter. This block 20 is adjusted toward and away from the center line of the pass of the mill by means of an adjusting screw 22, which is locked in adjusted position by means of a lock nut 23. By this means the rollers I l and i2 may be so disposed as to accommodate mandrel bars of various diameters.

The roller I is carried on a shaft 26 which is mounted in a bearing 21, the latter being slidably disposed in a housing 28. The bearing 21 is connected to a block 30 which is slidably disposed in the housing 28 and adjusted toward and away from the center line of the pass by means of an adjusting screw 32 which is locked in position by means of a lock nut 33.

Referring more particularly to Figure 3, it will be observed that the housings l8 and 28 have integrally formed therewith downwardly depending lever arms 35 and 36 respectively. These lever arms 35 and 36 provide central hub portions 31 and 38, respectively, through which there extends a shaft 39. Disposed below the shaft 39 is a block 42 which is mounted for reciprocation in a vertical guide 43. The block 42 carries a horizontal pin 45 to which there is pivotally connected one end of a link 46, the other end thereof being pivotally connected to the lower end of the lever arm 35. To the pin 45 there is also pivotally connected one end of a link 41, the other end thereof being pivotally connected to the lower end of the lever arm 36.

To the vertically reciprocable block 42 there is also connected the upper end of a piston rod 50, the piston of which is disposed in an air cylinder According to the foregoing construction and arrangement of parts, it will be understood that the operation of the air cylinder 5| will move the toggle links 46 and 41, and accordingly the lever arms 35 and 36, respectively, in such manner as to permit the respective housings l8 and 28 to move in scissors-like fashion to dispose the rollers I l--I2 and ID to advance toward, or recede from, the mandrel bar.

Admitting air to the bottom of the piston (not shown) on the lower end of the piston rod 50. brings the rollers lI-I2 and [0 to the bar-supporting position. As the tubular blank approaches the apparatus on the outlet bed of the mill, the operation admits air to the top of the piston 5| and the rollers Hl2 and I0 recede from the bar to admit passage of the tubular blank through that portion of the outlet bed of the mill.

Other and corresponding apparatus disposed at subsequent positions in the travel of the tubular blank over the outlet bed of the mill function in the same manner.

Referring to the diagrammatic showing of Figure 1 of the drawings, the tubular blank X is shown as having commenced its movement between the first series of rollers il-I2 and II], which are in receded position; but the next series of rollers lll2 and I0 are shown as supportin the mandrel bar 4. As stated hereinbefore, as soon as the forward end of the tubular blank approaches this seriesof rollers ii-l2 and I0. they will be receded in the manner previously described in connection with the first series thereof.

When the piston (not shown) occupying each of the air cylinders 5| has completed its forward stroke, it is stopped by a pad 55 carried on the upper end of the vertically reciprocable block 42 in the vertical guide 43. This pad 55 makes contact with the hubs 31 and 38, and the links 46 and 41 assume the position shown in Figure 4 (i. e., that of a toggle). This position of the various elements provides for great rigidity and maintenance of the rollers III, II and I2 in proper positions against the heavy stresses encountered. Due to the vertically reciprocable block 42 in the vertical guide 43, the travel of the piston rod 50 is stabilized.

As a result of the confinement of the vibration of the mandrel bar 4, there is less tendency toward variation in the wall thickness of the pipe or tube; and the life of the thrust bearing of the carriage 6 which supports the mandrel bar is lengthened.

While I have shown and described one specific embodiment of my invention, it will be understood that this embodiment is merely for the purpose of illustration and description and that various other forms may be devised within the scope of my invention, as defined inthe appended claims.

I claim:

1. A mil1 for rolling metallic pipes and tubes, comprising metal working rolls, an intermediately disposed mandrel, a mandrel bar for supporting the mandrel in the aforesaid position, a shaft disposed beneath and in parallelism with said mandrel bar, a pair of pivoted arms extending from opposite sides of said shaft, a support carried by each of said arms, a pair of spaced rollers carried by one of said supports, the axes of said pair of rollers being substantially parallel to each other and to the axis of said mandrel bar, at least one roller carried by the other of said pivoted arms, the axis of said last-named roller being likewise substantially parallel to the axis of said mandrel bar, means for raising said pivoted arms to cause said rollers to contact said mandrel bar, and means for adjusting one of said supports with respect to the arm by which it is carried.

2. A mill for rolling metallic pipes and tubes, comprising metal working rolls, an intermediately disposed mandrel, a mandrel bar for supporting the mandrel in the aforesaid position, a shaft disposed beneath and in parallelism with said mandrel bar, a pair of pivoted arms extending from opposite sides of said shaft, a. support carried by each of said arms, a pair of spaced rollers carried by one of said supports, means for ad 'usting said last-named support with respect to the arm by which it is carried, the axes of said pair of rollers being substantially parallel to each other and to the axis of said mandrel bar, at least one roller carried by the other of said pivoted arms, the axis of said last-named roller being likewise substantially parallel to the axis of said mandrel bar, and means for raising said pivoted :rms to cause said rollers to contact said mandrel WILLIAM T. MOHAN. 

